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At the time, the two were accused of playing God and interfering with nature.

Since then, the European Society for Human Reproduction and Embryology estimates that about five million babies have been born using the technique, which creates embryos in the laboratory before transferring them into a woman.

Experts say about 350,000 babies are born by IVF every year, mostly to people with infertility problems, single people and gay and lesbian couples.

"[Edwards] was an extraordinary scientist," said Dr Peter Braude, emeritus professor of obstetrics and gynecology at Kings College London, who was at Cambridge when Prof Edwards and Dr Steptoe were developing IVF.

"There was such hysteria around the kind of work he was doing," Dr Braude said, noting that Prof Edwards stopped his research for two years after he published details on how he had created embryos in the laboratory.

"He wanted to work out what the right thing to do was, whether he should continue or whether he was out on a limb," Dr Braude said.

Other scientists called Prof Edwards a visionary who forever changed the lives of people helped by IVF and the medical community.

"[His] inspirational work in the early 60s led to a breakthrough that has enhanced the lives of millions of people worldwide," said Mike Macnamee, chief executive of the IVF clinic that Prof Edwards and Dr Steptoe co-founded, in a statement.

"It was a privilege to work with him and his passing is a great loss to us all."